Field of the Invention
The present invention relates to an electrophotographic member included in an electrophotographic apparatus, and a process cartridge and an electrophotographic apparatus including the electrophotographic member.
Description of the Related Art
In electrophotographic apparatuses (electrophotographic copiers, fax machines, printers and the like of an electrophotographic type), an electrophotographic photosensitive member (hereinafter also referred to as “photosensitive member”) is charged by a charging roller, and is exposed to laser beams and the like to form an electrostatic latent image on the photosensitive member. A toner in a developing container is then applied onto a developing roller with a toner feed roller and a toner control member. Next, the toner is conveyed to a region to be developed with the developing roller. The electrostatic latent image on the photosensitive member is developed in or around the contact portion between the photosensitive member and the developing roller with the toner conveyed to the region to be developed. Subsequently, the toner on the photosensitive member is transferred onto a recording paper by a transferring unit, and is fixed by heat and pressure while the toner remaining on the photosensitive member is removed with a cleaning blade.
In such an electrophotographic apparatus, an electrophotographic member having an electro-conductive layer and used in a developing roller or a charging roller should have an electric resistance of about 105 to 109 Ω through control. The entire electrophotographic member should have a uniform and stable electro-conductivity for a long time. Predetermined electro-conductivity is given to the electro-conductive layer by an electro-conductive agent, e.g., electro-conductive particles such as carbon black or an ion conducting agent such as quaternary ammonium salts. Advantageously, an electro-conductive roller including electro-conductive particles such as carbon black barely contaminates other members in contact with the electro-conductive roller. On the other hand, the electro-conductive particles such as carbon black are difficult to homogeneously disperse, and generation of portions locally having low resistance is not readily prevented. Compared to the electro-conductive roller, an ion conductive roller including an ion conducting agent can reduce uneven electric resistance attributed to uneven dispersion of the electro-conductive agent, and has little portions locally having low resistance. For this reason, such an ion conductive roller used as a developing roller can uniformly develop a developer on the photosensitive member, and such an ion conductive roller used as a charging roller can uniformly charge the surface of the photosensitive member.
On the other hand, the ion conducting agent has migration properties, and therefore readily migrates after a long-term use from the electro-conductive layer to bleed out to the surface thereof. The migration of the ion conducting agent through the electro-conductive layer may change the electro-conductivity of the electrophotographic member after long-term use. The ion conducting agent bled out to the surface of the electro-conductive layer may adhere to the surface of the photosensitive member and the like in contact with the electrophotographic member to degrade the quality of electrophotographic images.
To solve the problem, Japanese Patent Application Laid-Open No. 2011-118113 discloses an ion liquid having two hydroxyl groups for fixing the ion liquid to an urethane resin composition to reduce bleeding out of the ion conducting agent.
Japanese Patent Application Laid-Open No. 2011-32397 discloses a durable antistatic resin having antistatic property overall which is prepared by bonding an active hydrogen-containing ion liquid to the resin via urethane bond or adding a polymerization product of an ion liquid containing an unsaturated ethylene group.
The present inventors have conducted research and found that in an electro-conductive layer including an ion conducting agent having two hydroxyl groups, the ion conducting agent was fixed to the electro-conductive layer to reduce the bleeding out of the ion conducting agent from the electro-conductive layer. However, the fixation of the ion conducting agent might reduce the electro-conductivity of the electro-conductive layer, so that the electro-conductivity required for the electrophotographic member was not attained, thus degrading the quality of electrophotographic images.